It started with defenseman Torey Krug, who had the primary assist on three of the power-play goals and scored the other one. Although the Bruins' top line of Brad Marchand, Patrice Bergeron and Pastrnak has yet to produce a 5-on-5 goal in the series, it was more dangerous Saturday.
Bergeron and Pastrnak scored power-play goals. Bergeron had a goal and two assists, all on the power play. Marcus Johansson also scored on the power play.
"I think it was just a night where everything went our way," said Krug, whose four points set a Bruins Cup Final record.
A lot has been going the Bruins' way on the power play in the Stanley Cup Playoffs.
They are 6-for-14 (42.9 percent) in the Final, 13-for-29 (44.8 percent) over the past two rounds and an NHL-best 23-for-64 (35.9 percent) for the playoffs. By comparison, the Blues are 1-for-10 on the power play in the Final, including 1-for-5 in Game 3.
"I think we just have a lot of different abilities and talents out there," said Marchand, who assisted on Krug's power-play goal. "We've been together for a while now, so we're comfortable with communicating and trying to look for different things. With Torey back there making the plays that he's making, we get lucky sometimes."
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Despite their power-play success in the playoffs, the Bruins were unhappy with their execution in the first two games of the Final. Boston went 2-for-10 on the man-advantage in splitting the first two games against St. Louis with each of the goals coming off zone-entry plays.
After reviewing some video, a decent portion of the Bruins practice on Friday was dedicated to working on the power play.
"We've really focused on entries, scoring, worked against Carolina," Bruins coach Bruce Cassidy said. "We try to exploit certain areas if we can. But O-zone, I thought we forced a lot of plays, didn't recover pucks well, we didn't have the support."
At one point during the practice, David Backes, who was subbing on the first unit while Bergeron took a maintenance day, scored on a deflection play similar to the one that Bergeron scored on to open the scoring 10:47 into the first period Saturday.
Krug took a wrist shot from the right point that Bergeron, who was stationed in the "bumper" spot at the inner rim of the right circle, tipped past goalie Jordan Binnington. That came 21 seconds into the Bruins' first power play, setting the tone for the night.
"I think we were taking what's there," said Bergeron, whose seven power-play goals are most in the playoffs. "I think maybe earlier we were forcing plays a little too much and tonight we put the puck on net and when you do that good things happen."